Today's Mercury Flyby To Be the First Since 1974

[Ian David]

By Marc Kaufman
Washington Post Staff Writer
Monday, January 14, 2008; Page A08

Right around noon today, if all goes as planned, a spacecraft called Messenger will swoop past the planet Mercury and begin two days of unprecedented picture-taking and data-collecting.

The flyby, the first visit to Mercury in more than 33 years by an emissary from Earth, will mark a key moment in a NASA mission that will ultimately place the first satellite into orbit around the tiny planet that sits closest to the sun.

The planetary science community is eagerly awaiting images and information that should shed light on some of the enduring mysteries about the planet -- such as where in the solar system it was formed and why its hard metal core is so large and its outer rock crust so scant, compared with those of Earth and the other rocky planets.

"Mercury is a difficult place to get to, and it's taken a long time to get back," said principal investigator Sean Solomon, who has worked on the mission for more than 11 years. "But now we're in place to learn things about one of our few sister rocky planets, and we're ready for some real surprises."


NASA's spacecraft Messenger, shown in this file image artist's drawing, is on a mission to the planet Mercury, the planet closest to the sun. (Ho - Reuters)

More:
http://www.washingtonpost.com/wp-dyn/content/article/2008/01/13/AR2008011302368.html?wpisrc=_rssnation/science

See also:

The Enduring Mysteries of Mercury
By Charles Q. Choi
Special to SPACE.com
posted: 14 January 2008
05:12 am ET

<snip>

The only spacecraft to ever visit the solar system's innermost world — NASA's Mariner 10 — mapped less than 45 percent of Mercury's surface, a heavily cratered landscape. This means more than half the planet is unknown to us, save for relatively poor observations from Earth-based radars.

<snip>

On the closest planet to the sun, where temperatures can reach more than 800 degrees Fahrenheit (425 degrees Celsius), there might surprisingly be ice. Ice is highly reflective to radar, and Earth-based radar suggests deposits of frozen water might be hidden in deep, dark craters at Mercury's poles that have never seen sunlight. This water might have come gassing up from within the planet or from meteorite impacts.

MESSENGER will search for hydrogen at the permanently shadowed floors of polar craters. If the spacecraft discovers any, MESSENGER may have found ice amidst an inferno.

Is Mercury shrinking?

Mercury could be shrinking as its core slowly freezes. Pictures from Mariner 10 revealed the planet's surface appears to have buckled from within, resulting in gigantic cliffs more than a mile high and hundreds of miles long biting into Mercury. MESSENGER will look for any evidence of such crumpling on the world's hidden side and will also study the planet's metal core by analyzing that world's magnetic field.

Vulcanoids?

Do a band of small asteroids dubbed "vulcanoids" lie inward of Mercury's orbit, hidden in the glare of the sun?

More:
http://www.space.com/scienceastronomy/080114-mm-mystery-mercury.html

[Orrex]

1. Forgive a dumb question

But why is it so difficult to get to Mercury? Is the heat a major factor? (Insert jokes about "then send the probe at night" here)